1. Field of the Invention
The present invention relates to a drying control method in a photograph processing apparatus for controlling a time interval to feed photosensitive materials to a drying section of a photograph processing apparatus.
2. Description of the Prior Art
In photograph processing apparatus, a photosensitive material accommodated in a magazine is drawn into a printing section where an image of a negative film is focused onto the photosensitive material by a printing beam emitted from a light source. After the printing, the photosensitive material is cut off and fed into a processor section where it is immersed into a developing tank, a fixing tank and a water washing (cleaning) tank in this order for the developing process, the fixing process and the water washing process, respectively.
A drying section is disposed downstream from the processor section. The photosensitive material having been processed through the above steps passes through the drying section so as to be dried, and then discharged into a take-out tray.
In the conventional drying section, the feeding speed and the feeding interval of photosensitive materials are get constant at all times regardless of the dimensions of the photosensitive materials, such as a width, length and area (hereinafter referred to collectively as a size). Accordingly, the drying section is required to have a capability enough to dry photosensitive materials even when they have a size as large as processable by the printing section and the processor section, and are fed successively.
However, the above drying section set constant in the feeding speed and the feeding interval regardless of the size of photosensitive materials is not preferable in that the photosensitive materials having a small size may be overly dried in some cases. For this reason, it has been proposed to set up two or more feeding paths different in their feeding distances within the drying section, and to change the feeding path dependent on the size of photosensitive materials. In other words, the photosensitive materials having a relatively small size are guided to pass through the feeding path of a shorter feeding distance, while the photosensitive materials having a relatively large size are guided to pass through the feeding path of longer feeding distance. This allows a proper drying time in accordance with the respective size of photosensitive materials.
Because the drying section is enlarged with the above proposed structure, another technique has also been conceived which can change a drying capability by the use of a single feeding path. More specifically, hot air heated by a heater is sent by a fan into the drying section in order to dry a photosensitive material. The photosensitive material is also directly contacted with rollers arrayed along the feeding path, so that moisture is wiped off of the photosensitive material by the rollers which are warmed with hot air. The drying of the photosensitive material is promoted through thermal conduction. Accordingly, the drying of the photosensitive material is affected by the temperature and flow rate of the hot air. By controlling the temperature and the flow rate of the hot air which is dependent on the size of the photosensitive materials, the proper drying conditions can be provided for any size of photosensitive materials even with the feeding distance and the feeding interval set constant.
However, in the case of controlling the temperature and flow rate of the warm air, sensors for precisely detecting the temperature and humidity in the drying section as well as the outside air etc., are required, which increases the number of parts used. Further, since the temperature and the humidity in the drying section are changed dependent on the process area of a photosensitive material between a time point immediately after the drying process and a time point immediately before start-up of the next drying process, it may happen in some cases that the temperature control fluctuates and the proper drying conditions cannot be achieved. More specifically, while photosensitive materials are always conveyed at a constant feeding speed, the drying section has increased humidity and reduced temperature after the photosensitive material having a larger size has been dried. This gives rise to a problem that the temperature in the drying section must be quickly raised before starting the process of the next photosensitive material, and if such a rise in the temperature is delayed, the photosensitive material is not dried sufficiently. On the other hand, since neither the temperature nor the humidity in the drying section are so changed after the photosensitive material having a smaller size has been dried, the drying section has the temperature and the humidity beyond respective predetermined ranges even if the heater and the fan are once turned off. This may result in a fear of over drying.